Hard drive cooling

With almost no airflow on them at the moment, my top HD runs at 50C and the one immedately below it runs at 49C. Both are 10 to 15C hotter than I'd like (per Google's research paper on HD temperatures - ideal is < 40C). Thinking about mounting a large diameter quiet fan next to the power supply to blow directly on them. Here's some options:

• http://www.vantecusa.com/product-cooling.html
• Nexus Frizzbee Inaudible HDD Cooler
• http://www.scythe-usa.com/support/support_temp/002/fan_spec.html